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The anatomical structure exhibited corresponding differences, the intercellular spaces being small in the alpine plant and large in the one grown in the lowlands, the wood-tissues strong in the first and weak in the second case.
*Production of the Intercellular Material.*—Though most of the cells of the body deposit to a slight extent this material, the greater part of it is produced by a single class of cells found in bone, cartilage, and connective tissue.
I. Intercellular material. *Complex Nature of the Tissues.*—To the unaided eye the tissues have the appearance of simple structures. The microscope, however, shows just the reverse to be true. When any one of the tissues is suitably prepared and carefully examined with this instrument, at least two classes of materials can be made out.
In this group each cell is usually separate and distinct from the others, but is attached to them, and is held in place by the intercellular material. *Protoplasm, the Cell Substance.*—The cell is properly regarded as an organized bit of a peculiar material, called protoplasm. This is a semi-liquid and somewhat granular substance which resembles in appearance the white of a raw egg.
Very commonly they have undergone a change of figure, most frequently a flattening which reduces them to scales, as in the epidermis and the epithelium. B. Simple, translucent, homogeneous solid, such as is found at the back of the cornea, or forming the intercellular substance of cartilage. C. The white fibrous element, consisting of very delicate, tenacious threads.
The cells and the intercellular material, though varying in their relative proportions, are present in all the tissues. *The Body a Cell Group.*—The biologist has found that the bodies of all living things, plants as well as animals, consist either of single cells or of groups of cells.
Very commonly they have undergone a change of figure, most frequently a flattening which reduces them to scales, as in the epidermis and the epithelium. B. Simple, translucent, homogeneous solid, such as is found at the back of the cornea, or forming the intercellular substance of cartilage. C. The white fibrous element, consisting of very delicate, tenacious threads.
Whether the appropriating agent be cell or nucleus, or a structureless solid like the intercellular substance of cartilage, the fact of its presence determines the separation of its proper constituents from the circulating fluid, so that even when we are wounded bone is replaced by bone, skin by skin, and nerve by nerve.
When there is a considerable amount of intercellular fibrous tissue, the tumour is called a fibro-sarcoma. [Illustration: FIG.
Even in the gray matter, though sometimes thickly distributed, the ganglion cells are never in actual contact one with another; they always lie embedded in intercellular tissues, which came to be known, following Virchow, as the neuroglia.
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